In an existing Long Term Evolution (LTE) system, network nodes mainly comprise a base station, User Equipment (UE) and a core network. Sending data to the UE from the base station is called downlink, and sending data to the base station from the UE is called uplink. For uplink, there are three channels: a Physical Random Access Channel (PRACH), a Physical Uplink Shared Channel (PUSCH) and a Physical Uplink Control Channel (PUCCH). Correspondingly, there are power calculation methods for the foregoing three channels; as a result, power control needs to be performed respectively for the three channels. The power control means that, in a mobile communication system, according to change of channels and a received signal level, via a feedback channel, the level of a transmitted signal is adjusted according to a certain control criterion, in order to decrease the overall interference level of the system. In an uplink in the LTE system, by means of the power control, path loss and shadow fading can be compensated, and interference between two multi-cell base stations can be decreased effectively; besides, by means of adjustment of the transmission power of mobile stations, the base station receives substantially equal signal power transmitted to the base station from all mobile stations in the cell, so that the near-far effect is overcome, and the transmission power of each mobile station is guaranteed to be most rational. Therefore, by means of the power control, the equipment energy can be saved, the service life of batteries can be prolonged, and the performance of cell edge users and the overall spectrum efficiency of the system also can be balanced.
In the current LTE system, two power control policies are employed, respectively: open-loop power control and closed-loop power control. In the open-loop power control, a TPC command sent by the base station side via a Downlink Control Information (DCI) is not changed, the UE side obtains a fixed power correction value via the TPC and determines an initial transmission power of the UE, to provide a basis for the closed-loop power control adjustment. The closed-loop power control further adjusts the power, the TPC command is employed to dynamically adjust the power correction value, as a compensation factor of power in order to control interference and meet conditions of channels. The closed-loop power control can apply to a PUSCH service channel and a PUCCH control channel. The open-loop power control does not need to feedback information, it can make quick response to the change of channels, and it has a relatively large dynamic adjustment range. The closed-loop power control can improve the precision of power adjustment, and it is an effective method to overcome asymmetric multi-path fading.
The closed-loop power control is implemented on the basis that the base station regularly sends a TPC command to the UE to feed back information, therefore, obtaining an accurate TPC command is a premise of excellent closed-loop power control, while the TPC command can be deduced from a Signal to Interference plus Noise Ratio (SINR) detected at the base station. In prior art, there is a method in which a current SINR value is compared with a preset target value and then a TPC command is selected according to a result of comparison, but the accuracy of the obtained TPC command is not high.